.\" Copyright (c) 2008 Pyun YongHyeon
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.Dd March 4, 2012
.Dt JME 4
.Os
.Sh NAME
.Nm jme
.Nd JMicron Gigabit/Fast Ethernet driver
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device miibus"
.Cd "device jme"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
if_jme_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
device driver provides support for JMicron JMC25x PCI Express
Gigabit Ethernet controllers and JMicron JMC26x PCI Express Fast
Ethernet controllers.
.Pp
All LOMs supported by the
.Nm
driver have TCP/UDP/IP checksum offload for both transmit and receive,
TCP segmentation offload (TSO), hardware VLAN tag stripping/insertion
features, Wake On Lan (WOL) and an interrupt coalescing/moderation
mechanism as well as a 64-bit multicast hash filter.
.Pp
The JMC25x also supports Jumbo Frames (up to 9216 bytes), which can be
configured via the interface MTU setting.
Selecting an MTU larger than 1500 bytes with the
.Xr ifconfig 8
utility configures the adapter to receive and transmit Jumbo Frames.
.Pp
The
.Nm
driver supports the following media types:
.Bl -tag -width ".Cm 10baseT/UTP"
.It Cm autoselect
Enable autoselection of the media type and options.
The user can manually override
the autoselected mode by adding media options to
.Xr rc.conf 5 .
.It Cm 10baseT/UTP
Set 10Mbps operation.
.It Cm 100baseTX
Set 100Mbps (Fast Ethernet) operation.
.It Cm 1000baseTX
Set 1000baseTX operation over twisted pair.
.El
.Pp
The
.Nm
driver supports the following media options:
.Bl -tag -width ".Cm full-duplex"
.It Cm full-duplex
Force full duplex operation.
.It Cm half-duplex
Force half duplex operation.
.El
.Pp
For more information on configuring this device, see
.Xr ifconfig 8 .
.Sh HARDWARE
The
.Nm
device driver provides support for the following Ethernet controllers:
.Pp
.Bl -bullet -compact
.It
JMicron JMC250 PCI Express Gigabit Ethernet controller
.It
JMicron JMC251 PCI Express Gigabit Ethernet with Card Read Host controller
.It
JMicron JMC260 PCI Express Fast Ethernet controller
.It
JMicron JMC261 PCI Express Gigabit Ethernet with Card Read Host controller
.El
.Sh LOADER TUNABLES
Tunables can be set at the
.Xr loader 8
prompt before booting the kernel or stored in
.Xr loader.conf 5 .
.Bl -tag -width "xxxxxx"
.It Va hw.jme.msi_disable
This tunable disables MSI support on the Ethernet hardware.
The default value is 0.
.It Va hw.jme.msix_disable
This tunable disables MSI-X support on the Ethernet hardware.
The default value is 0.
.El
.Sh SYSCTL VARIABLES
The following variables are available as both
.Xr sysctl 8
variables and
.Xr loader 8
tunables:
.Bl -tag -width "xxxxxx"
.It Va dev.jme.%d.tx_coal_to
This variable sets the maximum amount of time to delay
before sending a Tx completion interrupt, in microseconds.
The accepted range is 1 to 65535; the default is 100 (100us).
.It Va dev.jme.%d.tx_coal_pkt
This variable sets the maximum number of outgoing packets which may be
coalesced together into a single Tx completion interrupt.
The accepted range is 1 to 255; the default is 8.
.It Va dev.jme.%d.rx_coal_to
This variable sets the maximum amount of time to wait for
additional packets to arrive (for possible packet coalescing)
before firing an Rx completion interrupt, in microseconds.
The accepted range is 1 to 65535; the default is 100 (100us).
.It Va dev.jme.%d.rx_coal_pkt
This variable sets the maximum number of incoming packets which may be
coalesced into a single Rx completion interrupt.
The accepted range is 1 to 255; the default is 2.
.It Va dev.jme.%d.process_limit
This variable sets the maximum number of events that will be processed
in a single batch before the handler is requeued into a taskqueue.
The accepted range is 10 to 255; the default value is 128 events.
The interface does not need to be brought down and up again before
a change takes effect.
.El
.Sh SEE ALSO
.Xr altq 4 ,
.Xr arp 4 ,
.Xr miibus 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
driver was written by
.An Pyun YongHyeon Aq Mt yongari@FreeBSD.org .
It first appeared in
.Fx 7.1 .
.Sh CAVEATS
The
.Nm
driver tries to avoid unnecessary station address reprogramming for
controllers that use eFuse to store station address.
The number of times that eFuse can be safely reprogrammed is 16 at
most.
In addition, there is no way to restore the factory default station
address once the station address has been reprogrammed via eFuse.
It is highly recommended not to reprogram the station address and
it is the responsibility of the administrator to store the original station
address in a safe place when station address is changed.
.Pp
There are two known 1000baseT link establishment issues with JMC25x.
If the full mask revision number of JMC25x controller is less than
or equal to 4 and the link partner enabled the IEEE 802.3az Energy Efficient
Ethernet feature,  the controller will not be able to establish a
1000baseT link.
Also, if the length of the cable is longer than 120 meters, the controller
can not establish a 1000baseT link.
The known workaround for these issues is to force manual link
configuration with 100baseTX instead of relying on auto-negotiation.
The full mask revision number of controller can be checked with the
verbose kernel boot option.
Use the lower nibble of the chip revision number to get the
full mask revision of the controller.
